As processor technologies evolve, processors are becoming available with greater amounts of cores. To efficiently execute software, these cores may be tasked to perform different threads of a single application. Such an arrangement is referred to as cooperative threaded software. In modern cooperative threaded software, it is common for one thread to be waiting for another thread to complete. Conventionally, the processor on which the waiting thread is running burns active power while waiting. Still further, the time for waiting may be indeterminate, and thus the processor may not know for how long it should wait.
Another mechanism to enable a core to wait is to place the core into a wait state such as a low power state. To implement this task, an operating system (OS) is invoked. The OS may execute a pair of instructions referred to as a MONITOR instruction and an MWAIT instruction. Note that these instructions are not available to application level software. Instead, these instructions are used solely at the OS privilege level to set up an address range for monitoring and to enable the processor to enter into a low power state until the address range that is monitored is updated. However, there is significant overhead in entering into the OS to perform these instructions. This overhead is in the form of a high latency and furthermore can raise complexity, as OS scheduling issues may result in the waiting thread not being the next scheduled thread when it exits the wait state.